Sheryl, simply put, glass is melted sand. Potash (a potassium compound) and bicarbonate of soda are added to make the sand melt at a lower temperature. Today, as in older days, this is done in enormous furnaces, many of which are still in Europe’s Bavarian forest. Lime must also be added to the mixture; otherwise, the glass would eventually dissolve. Lime also increases the durability of glass. In fact, modern dishwashers are so hot that were it not for lime in the glass mixture, your wine glasses would melt.